Noninvasive cardiac output measurements in patients with pulmonary hypertension

Pulmonary hypertension (PH) is characterised by a progressive decline in cardiac output (CO) and right heart failure. NICOM (R) (noninvasive cardiac output monitor) is a bioreactance-based technology that has been broadly validated, but its specific application in right heart failure and PH is unknown. Cardiac catheterisation was performed in 50 consecutive patients with PH. CO measurements were performed using three different methods (thermodilution, Fick and NICOM) at baseline and after vasodilator challenge. We compared the precision (coefficient of variation) and accuracy of NICOM compared to thermodilution and Fick. The mean CO (L-min(-1)) at baseline as measured by the three methods was 4.73 +/- 1.15 (NICOM), 5.69 +/- 1.74 (thermodilution) and 4.84 +/- 1.39 (Fick). CO measured by NICOM was more precise than by thermodilution (3.5 +/- 0.3% versus 9.6 +/- 6.1%, p<0.001). Bland-Altman analyses comparing NICOM to thermodilution and Fick revealed bias and 95% limits of agreement that were comparable to those comparing Fick to thermodilution. All three CO methods detected an increase in CO in response to vasodilator challenge. CO measured via NICOM is precise and reliably measures CO at rest and changes in CO with vasodilator challenge in patients with PH. NICOM may allow for the noninvasive haemodynamic assessment of patients with PH and their response to therapy.